Solvent compositions are in widespread use throughout the world and in a wide variety of industrial applications. Certain fluorocarbons have been preferred components in solvent cleaning systems for many years. Trichlorotrifluoroethane has been one of the most widely used fluorocarbon solvents in recent years because it is generally effective as a solvent for many greases, oils, waxes and the like, and has therefore found widespread use for cleaning electric motors, compressors, heavy metal parts, delicate precision metal parts, printed circuit boards, gyroscopes, guidance systems, aerospace and missile hardware, aluminum parts and the like. Furthermore, trichlorotrifluoroethane is advantageous because it is nontoxic and nonflammable. Trichlorotrifluoroethane has two isomers: 1,1 2-trichloro-1 2,2-trifluoroethane (known in the art as CFC-113) and 1,1,1-trichloro-2,2,2-trifluoroethane (known in the art as CFC-113a).
Concern has increased in recent years about potential damage to the earth's ozone layer, and certain chlorine-based compounds have been identified as particularly problematic in this regard. CFC-113 is chemically stable and therefore has a relatively long life in the straposphere, and since the use CFC-113 as a solvent will frequently result in its release into the environment, it will frequently reach the stratosphere. In the stratosphere, CFC-113 gives rise to photolysis under the influence of sun light to generate chlorine radicals. The thus generated chlorine radicals combine with ozone, resulting in ozone depletion. Accordingly, the use of organic chlorine-based compounds such as CFCs has been severely restricted in many countries of the world by governmental regulation. Because CFC-113 has a high ozone destruction potential, a need has risen to replace it, and other compounds which exhibit similar environmentally detrimental properties.
In response to the need for stratospherically safe materials, substitutes have been developed and continue to be developed. Research Disclosure 14623 (June 1978) reports that 1,1-dichloro-2,2,2-trifiuoroethane (HCFC-123) is a useful solvent for degreasing and defluxing substrates. In the EPA “Findings of the Chlorofluorocarbon Chemical Substitutes International Committee”, EPA-600/9-88-009 (April 1988), it was reported on pages C-22 and C-23 that HCFC-123 and 1-fluoro-1,1-dichloroethane (HCFC-141b) have potential as replacements for CFC-113 as cleaning agents. Other hydrochlorofluorocarbon alkanes (HCFC alkanes) have been developed as potential replacements for CFC-113, including for example 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), 1-fluoro-1,1-dichloroethane (HCFC-141b), 1,1-dichloro-2,2,3,3,3-pentafluoropropane (HCFC-225ca) and 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC-225cb).
The preparation and use of fluorinated higher alkenes, that is fluorine-substituted alkenes having at least five carbon atoms, is known For example, U.S. Pat. No. 4,788,352—Smutny is directed to production tri-fluorinated C5 to C7 compounds having at least some degree of unsaturation. Such higher olefins are identified as being known to have utility as refrigerants, pesticides, dielectric fluids, heat transfer fluids, solvents, and intermediates in various chemical reactions. (See column I lines 11-22).
However, while many of the hydrochlorofluorocarbons described heretofore may have substantial solvent power with respect to certain oils and fats, many also have certain disadvantages. For example, some of these compounds may tend to attack substrates, particularly general-purpose plastics such as acrylic resins and ABS resins. Furthermore, the higher olefinic compounds described in Smutny may also be undesirable in certain applications because of the potential level of toxicity of such compounds which may arise as a result of their activity as pesticides. Also, such compounds may not be sufficiently volatile to act as effective solvents in certain vapor degreasing operations, and the relatively low vapor pressure of such compounds may make it difficult to remove the solvent composition from the parts being cleaned.
Flammability is another important property for many applications. That is, it is considered either important or essential in many applications, including particularly in solvent cleaning applications, to use compositions which are non-flammable. Thus, it is frequently beneficial to use in such compositions compounds which are nonflammable. As used herein, the term ‘nonflammable” refers to compounds or compositions which do not exhibit a flashpoint as measured by one of the standard flash point methods, for example ASTM-1310-86 ‘Flash point of liquids by tag Open-cup apparatus”. Unfortunately, many HFC's which might otherwise be desirable for use in solvent compositions are not nonflammable. For example, the fluoroalkane pentafluorobutane (HFC-365) is flammable and therefore not viable for use in many applications.
In many applications it is also highly desirable for solvent compositions to be relatively stable, that is, to be relatively resistant to possible chemical changes during storage and use. Applicants have come to recognize that CFC-113 is deficient in this regard because it tends to hydrolyze and form HCl. Furthermore, this problem is worsened because metal, which is typically present during any solvent cleaning operations, acts as a catalyst and causes the hydrolysis of CFC-113 to increase dramatically:
Applicants have thus come to appreciate a need for solvent compositions that are potentially useful in numerous applications, including degreasing applications, precision cleaning and electronics cleaning applications, dry cleaning applications, solvent etching applications, as a solvent in aerosols or other sprayable compositions, as carrier solvents for depositing lubricants and release agents and other solvent or surface treatment applications.